Organic-Inorganic Heterointerfaces for Ultrasensitive Detection of Ultraviolet Light

The performance of graphene field-effect transistors is limited by the drastically reduced carrier mobility of graphene on silicon dioxide (SiO₂) substrates. Here we demonstrate an ultrasensitive ultraviolet (UV) phototransistor featuring an organic self-assembled monolayer (SAM) sandwiched between an inorganic ZnO quantum dots decorated graphene channel and a conventional SiO₂/Si substrate. Remarkably, the room-temperature mobility of the chemical-vapor-deposition grown graphene channel on the SAM is an order-of-magnitude higher than on SiO₂, thereby drastically reducing electron transit-time in the channel. The resulting recirculation of electrons (in the graphene channel) within the lifetime of the photogenerated holes (in the ZnO) increases the photoresponsivity and gain of the transistor to ∼10⁸ A/W and ∼3 × 10⁹, respectively with a UV to visible rejection ratio of ∼10³. Our UV photodetector device manufacturing is also compatible with current semiconductor processing, and suitable for large volume production. (Figure Presented).